Warmaster Horus
Explorer
I've got an MC character who's highest spell slot is higher than his greatest castable spell level. As such he usually burns it to cast Aid as that is a great spell at higher levels.
Some reasons it is a save rather than an attack roll were already mentioned, but there is one other to consider: it's designed such so that it doesn't score critical hits.
So make sure before altering it that you want the results that you are getting (plate mail protecting against it better than leather rather than both being irrelevant, and a 5% chance of 20d6 +40 damage for a 6th level spell slot), rather than the one you thought of (ray = spell attack).
If the giant hits you for one meeeelion points of damage and you have no 1st level slots, a 3rd level slot casting of shield is definitely worth it.
If the evil mage keeps counterspelling your spell, casting it with a 5th level slot might be worth it, even if the spell itself gets no benefit from higher levels.
Casting hold monster with a 7th level slot will (maybe) get the rakshasa, since it is immune to magic of level 6 or lower.
If you are playing a game where collateral damage is a serious concern, perhaps because you spend a lot of time in town and/or near innocent civilians, then that explains why you might consider the smaller area of Burning Hands to be situationally useful. If you're in a dungeon where the walls are made of stone, or outdoors where there's plenty of open space, there's virtually zero merit to having such a small area of effect.I wouldn't describe wanting to avoid collateral damage as "extremely situational", personally, but that's just a nitpick.
This hinges on the existence of a situation where you would want to cast Burning Hands, even though you are high enough in level that you can cast Fireball, and that's not a situation which is likely to occur under the normal assumptions of gameplay.Even if there were literally no reason whatsoever to cast burning hands at 3rd level when you've prepared fireball, that wouldn't be a problem. It would mean you've prepped/learned both spells and made a conscious decision to go all-in on optimizing damage at every spell slot. Prepping just burning hands would mean you're willing to sacrifice some high-end damage but are planning on possibly doing something else with that 3rd-level spell slot. Prepping just fireball would mean you want the high-end damage and are planning on possibly doing something else with your 1st- and 2nd-level slots. All of these are interesting choices.
Does anyone else think it would be more interesting to have variable bonuses on level up? For instance, casting a fireball might have these options:
For each spell slot level higher than 3rd you can choose one of the following: increase damage by +1d6, increase the radius by 5 feet, or increase the range by 30 feet.